Coating compositions containing a highly fluorinated polymeric additive

ABSTRACT

A coating composition that forms a finish that is soil resistant and easily cleaned having a binder of 
     (A) an acrylic polymer of polymerized hydroxyl containing monomers of hydroxy alkyl (meth)acrylate having 1-4 carbon atoms in the alkyl group, and polymerized monomers from the group of alkyl (meth)acrylates having 1-18 carbon atoms in the alkyl group, styrene or any mixtures of the above and the acrylic polymer having a weight average molecular weight of about 2,000-20,000 determined by gel permeation chromatography, 
     (B) an acrylic polymeric additive of polymerized monomers from the group of alkyl (meth)acrylates having 1-18 carbon atoms in the alkyl groups, styrene or any mixtures of the above, and polymerized fluoro alkyl containing monomer represented by the formula ##STR1## where R is selected from the group of hydrogen or an alkyl group having 1-2 carbon atoms, X is a divalent radical and R f  is a fluoro alkyl containing group having 4-20 carbon atoms and the acrylic polymer having a weight average molecular weight of about 1,000-15,000 determined by gel permeation chromatography, and 
     (C) an organic crosslinking agent; and 
     where a cured layer of the coating of the composition has a combination of advancing water contact angle of at least 100° and a hexadecane advancing contact angle of at least 40°. Articles coated with the composition also are part of this invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is directed to a coating composition of an acrylicpolymer and a crosslinking agent such as a polyisocyanate or a melaminecrosslinking agent and contains a highly fluorinated polymeric additiveand forms a finish that remains relatively dirt free under exterior useconditions and is easily cleaned when soiled, for example by washingwith water.

2. Description of the Prior Art

Acrylic polymer containing coating compositions crosslinlked with apolyisocyanate are well known as shown in Vasta U.S. Pat. No. 3,558,564issued Jan. 26, 1971 and Krueger U.S. Pat. No. 4,156,678 issued May 29,1979. Coating compositions of blends of acrylic polymers and acrylicpolymer containing fluorocarbon constituents that form antiicingcoatings are well known. Clear coats containing acrylic polymers havingsmall amounts of fluorocarbon constituents that are applied overmetallic base coats to provide auto finishes that have goodweatherability, have high water and oil repellence and stain resistanceare shown in Sugimura et al U.S. Pat. No. 4,812,337 issued Mar. 14,1989.

Fluorinated polyurethanes that are used as soil release agents are shownin Gresham U.S. Pat. No. 3,759,874 issued Sep. 18, 1973. Polyurethanesof fluorinated isocyanates that are used as adhesives are shown inMitsch et al U.S. Pat. No. 3,972,856 issued Aug. 3, 1976. Protectivecoatings of fluorinated polyurethanes of fluorinated diols or triols areshown in Re et al U.S. Pat. No. 4,782,130 issued Nov. 1, 1988.

There is a need for a fluoro carbon containing additive that can beadded to a conventional coating composition that will form a coatingcomposition that is high in solids, that can be applied withconventional equipment and cures to a hard, tough, durable andweatherable finish without baking at elevated temperatures and thefinish is soil resistant and is easily cleaned. Preferably, the coatingcomposition has a low content of fluorocarbon constituents which reducesthe cost of the composition since the fluorocarbon constituent of thecomposition is expensive.

SUMMARY OF THE INVENTION

A coating composition containing about 45-80% by weight of a binder and20-55% by weight of a carrier liquid; wherein the binder contains

(A) an acrylic polymer of polymerized hydroxyl containing monomers ofhydroxy alkyl (meth)acrylates having 1-4 carbon atoms in the alkylgroup, and polymerized monomers from the group of alkyl (meth)acrylateshaving 1-18 carbon atoms in the alkyl groups, styrene or any mixtures ofthe above and the acrylic polymer has weight average molecular weight ofabout 2,000-20,000 determined by gel permeation chromatography,

(B) an acrylic polymeric additive containing about 5-90% by weight,based on the weight of the acrylic polymer additive, of polymerizedmonomers from the group of alkyl (meth)acrylates having 1-18 carbonatoms in the alkyl group, styrene or any mixtures of the above and10-95% by weight, based on the weight of the acrylic polymeric additive,of polymerized fluoro alkyl containing monomer represented by theformula ##STR2## where R is selected from the group consisting ofhydrogen or an alkyl group having 1-2 carbon atoms, X is a divalentradical and R_(f) is a fluoro alkyl containing group having 4-20 carbonatoms and the acrylic polymeric additive has a weight average molecularweight of about 1,000-15,000 determined by gel permeationchromatography, and

(C) an organic crosslinking agent; and

where a cured layer of the coating of the composition has a combinationof advancing water contact angle of at least 100° and a hexadecaneadvancing contact angle of at least 40°.

Articles coated with the composition also are part of this invention.

DETAILED DESCRIPTION OF THE INVENTION

Coating compositions of this invention are primarily used as a clearcoat over a pigmented base coat containing solid color pigments ormetallic flake pigments or mixtures thereof. These coating compositionalso can be used as a conventional pigmented compositions. Conventionalspray equipment can be used to apply theses coating compositions and thecompositions can be cured at ambient temperatures or slightly elevatedtemperatures which decreases drying time. The resulting finish hasexcellent gloss and distinctness of image and excellent dirt, water andoil repellency, is easily cleaned by washing with water or with a watersurfactant mixture or can be wiped clean and has good stain resistanceand weatherability.

Preferably, the coating composition is a clear coating composition, i.e.containing no pigments or only a small amount of transparent pigment.The composition has a relatively high solids content of about 45-80% byweight of binder and about 20-55% by weight of a carrier which usuallyis an organic carrier that can be a solvent for the binder or a mixtureof solvents and non solvent which would form a non aqueous dispersion.The composition has a low VOC (volatile organic content) and meetscurrent pollution regulations.

The coating composition when applied to a substrate and fully cured hasa water advancing contact angle of at least 100°, preferably 100-120°and a hexadecane advancing contact angle of at least 40°, preferably45-85° and more preferably 60-85°.

Contact angles are measured by the Sessile Drop Method which is fullydescribed in A. W. Adamson, The Physical Chemistry of Surfaces, 5 thEd., Wiley & Sons, New York, 1990, Chapter II which is herebyincorporated herein by reference.

Briefly, in the Sessile Drop Method, a drop of liquid, either water orsolvent, is placed on a surface and the tangent is precisely determinedat the point of contact between the drop and the surface. An advancingangle is determined by increasing the size of the drop of liquid and areceding angle is determined by decreasing the size of the drop ofliquid. Additional information on the equipment and procedure needed tomeasure these contact angles are more fully described in R. H. Dettre,R. E. Johnson Jr., Wettability, Ed. by J. C. Berg, Marcel Dekker, NewYork, 1993, Chapter 1 which is incorporated herein by reference.

The relationship between water and organic liquid contact angles andcleanability and dirt retention is described in chapters XII and XIII ofA. W. Adamson, above. In general, the higher the contact angle the moredirt or soil resistant the surface is and the easier the surface is toclean. The coating composition of this invention has a high contactangle and is resistant to dirt and soil and is easily cleaned.

Typically, the coating composition contains about 30-89% by weight,based on the weight of the binder, of an acrylic polymer, 1-20% byweight, based on the weight of the binder, of an acrylic polymericadditive and 10-50% by weight, based on the weight of the binder, of acrosslinking agent.

The acrylic polymer used in the coating composition is prepared byconventional polymerization techniques in which the monomers, solvent,and polymerization initiator are charged over a 1-24 hour period oftime, preferably in a 2-8 hour time period, into a conventionalpolymerization reactor in which the constituents are heated to about60-175° C., preferably about 140-170° C. The acrylic polymer formed hasa weight average molecular weight of about 2,000-20,000, preferablyabout 5,000-10,000.

Molecular weights referred to herein are determined by gel permeationchromatography using polystyrene as the standard.

Typical polymerization initiators that are used in the process are azotype initiators such as azo-bis-isobutyronitrile,1,1'-azo-bis(cyanocyclohexane), peroxy acetates such as t-butylperacetate, peroxides such as di-t-butyl peroxide, benzoates such ast-butyl perbenzoate, octoates such as t-butyl peroctoate and the like.

Typical solvents that can be used in the process are ketones such asmethyl amyl ketone, methyl isobutyl ketone, methyl ethyl ketone,aromatic hydrocarbons such as toluene, xylene, alkylene carbonates suchas propylene carbonate, n-methyl pyrrolidone, ethers, esters, acetatesand mixture of any of the above.

Typical polymerizable monomers that are used to form the acrylic polymerare alkyl (meth)acrylates, meaning alkyl acrylates and alkylmethacrylates, having 1-18 carbon atoms in the alkyl group such asmethyl methacrylate, ethyl acrylate, ethyl methacrylate, propylacrylate, propyl methacrylate, isopropyl methacrylate, butyl acrylate,isobutyl methacrylate, butyl methacrylate, t-butyl methacrylate, pentylacrylate, pentyl methacrylate, hexyl acrylate, hexyl methacrylate, octylacrylate, octyl methacrylate, nonyl acrylate, nonyl methacrylate, decylacrylate, decyl methacrylate, lauryl acrylate, lauryl methacrylate,stearyl acrylate, stearyl methacrylate and the like; other usefulmonomers are styrene, alpha methyl styrene, acrylamide, methacrylamide,acrylonitrile, hydroxy methacrylamide and the like; or any mixtures ofthese monomers. Hydroxy alkyl (meth)acrylates meaning hydroxy alkylacrylates and hydroxy alkyl methacrylates having 1-4 carbon atoms in thealkyl groups that can be use are hydroxy methyl acrylate, hydroxy methylmethacrylate, hydroxy ethyl acrylate, hydroxy ethyl methacrylate,hydroxy propyl methacrylate, hydroxy propyl acrylate, hydroxy butylacrylate, hydroxy butyl methacrylate and the like.

Preferred acrylic polymers which form high quality coatings containpolymerized monomers of an alkyl methacrylate having 2-6 carbon atoms inthe alkyl group, an alkyl acrylate having 2-8 carbon atoms in the alkylgroup, a hydroxy alkyl acrylate having 2-4 carbon atoms in the alkylgroup and styrene. One particularly preferred polymer contains butylmethacrylate, butyl acrylate. styrene, and hydroxy propyl acrylate.

The acrylic polymeric additive used in the coating composition isprepared similarly to the above acrylic polymer by conventionalpolymerization techniques in which the monomers, except the fluoroalkylcontaining monomer, solvent, and polymerization initiator are chargedover a 1-24 hour period of time, preferably in a 2-8 hour time period,into a conventional polymerization reactor in which the constituents areheated to about 60-175° C., preferably about 140-170° C. The polymerformed has a weight average molecular weight of about 1,000-15,000,preferably about 1,000-10,000.

The aforementioned polymerization initiators, solvents and the otheraforementioned monomers such as alkyl (meth)acrylates, with theexception of hydroxy alkyl (meth)acrylates can be used to prepare theadditive including acrylamide, methacrylamide, acrylonitrile, and thelike. The acrylic polymeric additive does not contain hydroxyconstituents such as hydroxy alkyl (meth)acrylic. The acrylic polymericadditive can also contain polymerized acetoacetoxy (meth)acrylatemonomers having 1-4 carbon atoms in the alkyl group such as acetoacetoxyethyl methacrylate which is preferred. acetoacetoxy methyl acrylate,acetoacetoxy propyl methacrylate, acetoacetoxy ethyl acrylate,acetoacetoxy butyl methacrylate, acetoacetoxy isobutyl acrylate and thelike.

The acrylic polymeric additive contains about 5-90% by weight of theaforementioned alkyl (meth)acrylate, styrene and the like and 10-95% byweight of fluoro alkyl containing monomers.

One preferred acrylic polymeric additive contains about 10-45% by weightof aceto acetoxy alkyl (meth)acrylate, 5-80% by weight of theaforementioned alkyl (meth)acrylate, styrene and the like and 10-50% byweight of fluoro alkyl-containing monomers

The fluoroalkyl containing monomers that are used in the acrylic polymeradditive are represented by the formula ##STR3## where R is hydrogen oran alkyl group having 1-2 carbon atoms, X is a divalent radical,preferably, a hydrocarbon group having 2-20 carbon atoms, and morepreferably, X is (CH₂)_(n) where n is an integer of 1-18 and R_(f) is afluoroalkyl containing group having 4-20 carbon atoms and preferably astraight chain or branched chain fluoroalkyl group having 4-20 carbonatoms which optionally can contain an oxygen atom.

Typically useful fluoroalkyl containing monomers are perfluoro methylethyl methacrylate, perfluoro ethyl methacrylate, perfluoro butyl ethylmethacrylate, perfluoro pentyl ethyl methacrylate, perfluoro hexyl ethylmethacrylate, perfluoro octyl ethyl methacrylate, perfluoro decyl ethylmethacrylate, perfluoro lauryl ethyl methacrylate, perfluoro stearylethyl methacrylate, perfluoro methyl ethyl acrylate, perfluoro ethylethyl acrylate, perfluoro butyl ethyl acrylate, perfluoro pentyl ethylacrylate, perfluoro hexyl ethyl acrylate, perfluoro octyl ethylacrylate, perfluoro decyl ethyl acrylate, perfluoro lauryl ethylacrylate, perfluoro stearyl ethyl acrylate, and the like. Preferred areperfluoro alkyl ethyl methacrylates wherein the perfluoroalkyl groupcontains 4-20 carbon atoms.

Other useful fluoroalkyl containing monomers are represented by theformula ##STR4## where R is as defined above,

R¹ is a fluoroalkyl group having 4-12 carbon atoms,

R² is an alkyl group having 1-4 carbon atoms and

n is an integer of 1-4.

Typical of these monomers are the following: ##STR5##

Preferred acrylic polymeric additives which form high quality coatingscontain polymerized monomers of an alkyl methacrylate having 2-6 carbonatoms in the alkyl group, an alkyl acrylate having 2-8 carbon atoms inthe alkyl group, acetoacetoxy alkyl (meth)acrylate having 1-4 carbonatoms in the alkyl group, styrene and perfluoroalkyl ethyl methacrylatehaving 4-20 carbon atoms in the alkyl group. One particularly preferredpolymer contains butyl methacrylate, butyl acrylate, styrene,acetoacetoxy ethyl methacrylate and the above perfluoroalkyl containingmonomer.

Other useful acrylic polymer additives contain polymerized monomers ofan alkyl methacrylate having 2-6 carbon atoms in the alkyl group, analkyl acrylate having 2-8 carbon atoms in the alkyl group, styrene, analkylene glycol methacrylate, an acetoacetoxy alkyl methacrylate having1-4 carbon atoms in the alkyl group and a perfluoro alkyl ethylmethacrylate having 4-20 carbon atoms in the alkyl group. Typical ofsuch polymers are butyl methacrylate, butyl acrylate, acetoacetoxy ethylmethacrylate, ethylene triglycol methacrylate and the above perfluoroalkyl ethyl methacrylate monomer.

The coating composition contains an organic crosslinking agent.Preferably, an organic polyisocyanate crosslinking agent or an alkylatedmelamine crosslinking agent.

Any of the conventional aromatic, aliphatic, cycloaliphatic isocyanates,trifunctional isocyanates and isocyanate functional adducts of polyolsand diisocyanates can be used. Typically useful diisocyanates are1,6-hexamethylene diisocyanate, isophorone diisocyanate,4,4'-biphenylene diisocyanate, toluene diisocyanate, bis cyclohexyldiisocyanate, tetramethylene xylene diisocyanate, ethyl ethylenediisocyanate, 2,3-dimethyl ethylene diisocyanate, 1-methyltrimethylenediisocyanate, 1,3-cyclopentylene diisocyanate, 1,4-cyclohexylenediisocyanate, 1,3-phenylene diisocyanate, 1,5-naphthalene diisocyanate,bis-(4-isocyanatocyclohexyl)-methane, 4,4'-diisocyanatodiphenyl etherand the like.

Typical trifunctional isocyanates that can be used are triphenylmethanetriisocyanate, 1,3,5-benzene triisocyanate, 2,4,5-toluene triisocyanateand the like. Oligomers of diisocyanates also can be used such as thetrimer of hexamethylene diisocyanate which is sold under the tradename"Desmodur" N-3390.

Isocyanate functional adducts can be used that are formed from anorganic polyisocyanate and a polyol. Any of the aforementionedpolyisocyanates can be used with a polyol to form an adduct. Polyolssuch as trimethylol alkanes like trimethylol propane or ethane can beused. One useful adduct is the reaction product of tetramethylxylidinediisocyanate and trimethylol propane and is sold under the tradename"Cythane" 3160.

A fluorinated organic polyisocyanate crosslinking agent which is anadduct of a fluorinated monofunctional alcohol and one of theaforementioned conventional organic polyisocyanate can also be used.About 0.1-33 mole percent of active isocyanate groups of one of thepolyisocyanate are reacted with the fluorinated monofunctional alcoholto form the fluorinated organic polyisocyanate. Typically, theconstituents are reacted with a catalyst for about 0.1-4 hours at atemperature of about 50-120° C. to form the adduct.

Typical fluorinated monofunctional alcohols used to form the isocyanatefunctional adducts are represented by the formula ##STR6## where R_(f)is a fluoroalkyl containing group having at least 4 carbon atoms andpreferably a straight chain or branched chain fluoroalkyl group having4-20 carbon atoms which optionally can contain oxygen atoms as ethergroups or can contain 1-5 chlorine atoms or 1-5 hydrogen atoms.Preferably, R_(f) is a perfluoroalkyl group having 4-20 carbon atoms andmost preferably, R_(f) is a perfluoroalkyl group containing 6-12 carbonatoms. Y is a divalent radical, preferably --CH₂ CH₂ O--, --SO₂ N(R⁴)CH₂CH₂ O--, --CH₂ --, --O--, CH₂ O-- where R⁴ is an alkyl group preferablyhaving 1-4 carbon atoms. R³ is H or an alkyl group having 1-4 carbonatoms, H and methyl being preferred, n is 0-1 and in is 1-30, providedthat if n is 0, then m must be greater than or equal to 1; if Y is--O--, m must be greater than or equal to 1; m preferably is 1-20.

The following are preferred fluorinated monofunctional alcohols:##STR7## where R_(f) is a perfluoroalkyl group having 6-12 carbon atomsand n is 5-15; ##STR8## where n is 1-6; ##STR9## where R⁵ is an alkylgroup having 1-4 carbon atoms and n is 1-30; ##STR10## where n is 0-10and m is 1-20; and R_(f) --CH₂ --CH₂ --OH where R_(f) is describedabove.

Alkylated melamine crosslinking agents can also be used in thecomposition. These crosslinking agents are generally partially or fullyalkylated melamine formaldehyde compounds that may be monomeric orpolymeric and if polymeric have a degree of polymerization of about 1-3.Typical alcohols used to alkylate these resins are methanol, ethanol,propanol, butanol, isobutanol and the like. Typically useful alkylatedmelamine crosslinking agents are available commercially include thefollowing: Cymel® 301, 350, 373, 385, 1161, or 1168, or Resimine® 714,730, 731, 735 and 745. Usually, a strong acid catalyst or its salt isadded in an amount of about 1-3% by weight, based on the weight of thebinder, to lower the curing temperature. Para toluene sulfonic acid,dodecyl benzene sulfonic acid, phosphoric acid or the amine or ammoniumsalts of these acid can be used.

To improve weatherability of a clear coating composition about 0.1-10%by weight, based on the weight of the binder, of ultraviolet lightstabilizers, screeners, quenchers and antioxidants usually are added.Typical ultraviolet light screeners and stabilizers include thefollowing:

Benzophenones such as hydroxy dodecyl oxy benzophenone, 2,4-dihydroxybenzophenone, hydroxy benzophenones containing sulfonic acid groups andthe like.

Benzoates such as dibenzoate of diphenylol propane, tertiary butylbenzoate of diphenylol propane and the like.

Triazines such as 3,5-dialkyl-4-hydroxy phenyl derivatives of triazine,sulfur containing derivatives of dialkyl-4-hydroxy phenyl triazine,hydroxy phenyl-1,3,5-triazine and the like.

Triazoles such as 2-phenyl-4-(2,2'-dihydroxybenzoyl)-triazole,substituted benzotriazoles such as hydroxy-phenyltriazole and the like.

Hindered amines such as bis(1,2,2,6,6 pentamethyl-4-piperidinylsebacate), di 4(2,2,6,6,tetramethyl piperidinyl)! sebacate and the likeand any mixtures of any of the above.

When using an isocyanate crosslinking agent, the coating compositioncontains a sufficient amount of a catalyst to cure the composition atambient temperatures. Generally, about 0.01-2% by weight, based on theweight of the binder, of catalyst is used. Typically useful catalystsare triethylene diamine and alkyl tin laurates such as dibutyl tindilaurate, dibutyl tin diacetate, tertiary amines and the like.Preferred is dibutyl tin dilaurate.

Generally, flow control agents are used in the composition in amounts ofabout 0.1-5% by weight, based on the weight of the binder, such aspolyacrylic acid, polyalkylacrylates, polyether modified dimethylpolysiloxane copolymers and polyester modified polydimethyl siloxane.

When the coating composition is used as a clear coating compositionusually over a pigmented base coat, it may be desirable to use pigmentsin the coating composition which have the same refractive index as thedried coating. Typically useful pigments have a particle size of about0.015-50 microns and are used in a pigment to binder weight ratio ofabout 1:100 to 10:100 and are inorganic siliceous pigments such assilica pigment having a refractive index of about 1.4-1.6.

It is highly desirable to use at least some fluorinated organicpolyisocyanate crosslinking agent, as described above, in the pigmentedbase coat over which the clear coat of this invention is applied tosignificantly reduce cratering of the base coat. Usually, about 5-40% byweight, based on the weight of the binder, of the fluorinatedpolyisocyanate is used in the base coat.

When the coating composition is used as a clear coating on a vehiclesuch as a car, truck, bus, train, or on construction equipment,industrial equipment, structures such as tanks, bridges, exterior orinterior of buildings, a basecoating which may be either a solvent basedor waterbased composition is first applied and then the clear coating isapplied usually by conventional means such as spraying or electrostaticspraying. The clear coating is dried and cures at ambient temperaturesbut moderately high temperatures of up to about 90° C. can be used toshorten drying time.

The coating composition can be used as a conventional pigmented coatingcomposition containing pigments in a pigment to binder weight ratio ofabout 0.1-100. The composition can be used to coat any of theaforementioned items and substrates and provides a finish that has goodgloss and is weatherable, tough and hard.

The following examples illustrate the invention. All parts andpercentages are on a weight basis unless otherwise specified. Molecularweight was determined by gel permeation chromatography using polystyreneas the standard.

EXAMPLE 1

A fluorinated acrylic polymeric additive solution A was prepared bycharging the following constituents into a reactor equipped with a heatsource, a thermometer and a stirrer:

    ______________________________________                                                               Parts By Weight                                        ______________________________________                                        Portion 1                                                                     Methyl amyl ketone       465.83                                               Portion 2                                                                     Butyl methacrylate monomer (BMA)                                                                       478.35                                               Styrene monomer (S)      205.01                                               Acetoacetoxy methacrylate monomer (AAEMA)                                                              410.01                                               Fluoro alkyl ethyl methacrylate monomer (FAMA)-                                                        273.67                                               (fluoro alkyl group containing C-4 about 5%, C-6                              about 30%, C-8 about 30%, C-10 about 20%, C-12                                about 10%, C-14 about 5%)                                                     Methyl amyl ketone       3.14                                                 Portion 3                                                                     T-butyl peroxy acetate   45.93                                                Methyl amyl ketone       76.27                                                Portion 4                                                                     Methyl amyl ketone       42.12                                                Total                    2000.33                                              ______________________________________                                    

Portion 1 was charged into the reaction vessel and blanketed withnitrogen and Portion 2 was premixed and added over a 240 minute periodwhile holding the resulting mixture at its reflux temperature of about150° C. Portion 3 was premixed and added at the same time as Portion 2to the reaction mixture over a 255 minute period and then Portion 4 wasadded and the reaction mixture was held at its reflux temperature for anadditional 60 minutes. The resulting polymer solution was cooled to roomtemperature.

The resulting acrylic polymeric additive solution A had a weight solidscontent of about 70%, a polymer of BMA/S/AAEMA/FAMA in the followingpercentages 35.0%/15.0%/30%/20.0% and the polymer had a weight averagemolecular weight of about 6,500.

A fluorinated acrylic polymeric additive solution B was prepared usingthe same constituents and procedure except the ratio of monomers wherechanged and the resulting polymer had the following compositionBMA/S/AAEMA/FAMA 30%/15%/17%/30% and a weight average molecular weightof about 7,000.

An acrylic polymer I solution was prepared by charging the followingconstituents into a reactor equipped with a heat source, a thermometerand a stirrer:

    ______________________________________                                                            Parts By Weight                                           ______________________________________                                        Portion 1                                                                     Methyl amyl ketone    699.20                                                  Portion 2                                                                     Butyl methacrylate monomer (BMA)                                                                    583.80                                                  Styrene monomer (S)   307.28                                                  Butyl acrylate monomer (BA)                                                                         343.20                                                  Hydroxy propyl acrylate monomer (HPA)                                                               783.60                                                  Methyl amyl ketone    4.72                                                    Portion 3                                                                     T-butyl peroxy acetate                                                                              69.01                                                   Methyl amyl ketone    114.59                                                  Portion 4                                                                     Methyl amyl ketone    33.28                                                   Total                  2938.68                                                ______________________________________                                    

Portion 1 was charged into the reaction vessel and blanketed withnitrogen and Portion 2 was premixed and added over a 240 minute periodwhile holding the resulting mixture at its reflux temperature of about150° C. Portion 3 was premixed and added at the same time as Portion 2to the reaction mixture over a 255 minute period. Portion 4 was addedand the reaction mixture was held at its reflux temperature for anadditional 60 minutes. The resulting polymer solution was cooled to roomtemperature.

The resulting acrylic polymer solution I had a weight solids content ofabout 70%, a polymer of BMA/S/BA/HPA in the following percentages30%/15.0%/17%/38% and the polymer had a weight average molecular weightof about 7,000.

A clear acrylic composition I was prepared as follows:

    ______________________________________                                                               Parts by Weight                                        ______________________________________                                        Portion 1                                                                     Methyl ethyl ketone      2.54                                                 Toluene                  2.67                                                 Dibasic acid ester (ester mixture of adipic acid,                                                      1.79                                                 glutaric acid and succinic acid)                                              Butyl Cellosolve Acetate 4.96                                                 Portion 2                                                                     Acrylic polymer I solution (prepared above)                                                            72.79                                                Portion 3                                                                     Resiflow S (Acrylic polymer flow additive)                                                             0.35                                                 "Tinuvin" 328 - 2-(2-hydroxy-3,5-ditertiary amyl                                                       5.58                                                 phenol)-2H-benzotriazole)                                                     "Tinuvin" 292 - (1,2,2,6,6-pentamethyl-4-piperidinyl)-                                                 0.87                                                 sebacate                                                                      Dibutyl tin dilaurate    0.92                                                 PM acetate               7.38                                                 Total                    100.00                                               ______________________________________                                    

The constituents of Portion 1 were charged into a mixing vessel in theorder shown with continuous mixing. Portion 2 was added and mixed for 15minutes. The constituents of Portion 3 were charged into the mixingvessel in the order shown with constant mixing. The resultingcomposition had a solids content of about 53.5%.

A clear coating composition I (control) was prepared by mixing the aboveclear acrylic composition I with a polyisocyanate solution in a 3/1volume ratio. The polyisocyanate solution contains 90% by weight of thetrimer of lo hexamethylene diisocyanate and 10% by weight of a solventof n-butyl acetate/Aromatic 100 solvent in a 1:1 ratio. Clear coatingcomposition A was prepared by mixing the above clear coating compositionI with 5.0%, by weight of the fluorinated acrylic polymeric additivesolution A, prepared above.

Similarly, clear coating compositions B and C. were prepared by mixingthe above clear coating composition respectively with 2.0%, and 5.0%, byweight of the fluorinated acrylic polymeric additive solution B,prepared above.

A set of two phosphated cold rolled steel panels that had been coatedwith a cured electrocoating primer composition of a polyepoxy hydroxyether resin crosslinked with a polyisocyanate were spray coated with awhite basecoat coating composition of an acrylic polymer containing anorganic polyisocyanate crosslinking agent to a dry film thickness ofabout 18-23 microns. The basecoat was allowed to stand for about 10minutes to allow solvent to evaporate and then the above prepared clearcoating composition I (control) was spray applied. Two coats wereapplied with a solvent evaporation time of 2 minutes between theapplication of each coat. The resulting film was dried at about 83° C.for about 30 minutes. The dry film thickness of the clear coat was about44-56 microns. The resulting clear coat was smooth and essentially freeof craters and had an excellent appearance.

Clear coating compositions A-C were applied in the same manner toseparate phosphated steel panels coated as above and then cured asabove. In each case, the resulting clear coat was smooth and essentiallyfree of craters and had an excellent appearance.

The following tests were conducted on each of the panels and the resultsare shown in Table I:

    ______________________________________                                        Advancing and Receding contact angles for water and hexadecane.               ______________________________________                                                 Gloss measured at 20°.                                                 DOI distinctness of image.                                                    Haze                                                                          Hardness (measured in knoops)                                                 L, a, b, color angle values.                                                  Soil Resistance Test.                                                ______________________________________                                    

Soil Resistance Test

A soil substitute was prepared by blending 10 g of Nujol (mineral oil),20 g of carbon black, 500 ml of heptane and 1 liter of "Surlyn" polymerbeads (polymer of an acrylic ionomer). The resulting suspension wasthoroughly mixed and then the heptane solvent was stripped off using avacuum stripper.

A 2.54 cm length of 7.62 cm OD polyvinyl chloride pipe was place on thesurface of the test panel. Three grams of the above prepared soilsubstitute was poured into the pipe and gently rolled around on thesurface of the test panel for a total of fifty rotations. The soilsubstitute was poured off and the pipe segment was removed. The testpanel was then tapped sharply twice on the side of a trash can to removelightly adhered dirt. The amount of dirt remaining on the panel wasmeasured in delta E units with a color analyzer.

The data in Table I shows that clear coating compositions A-C thatcontain an additive of a fluorinated acrylic polymer have a highercontact angle for water and for hexadecane in comparison to the controlwhich did not contain the additive. The Soil Resistance Test shows thatcoating compositions A-C that contained the fluorinated acrylic polymeradditive provides a finish which is resistant to soiling and also iseasily washed or wiped clean in comparison to the clear coatingcomposition made from the control which did not contain a fluorinatedacrylic polymer additive. The control had low contact angles andexhibited poor soil resistance in the Soil Resistance Test and poorcleanability. All of the coating compositions with and without thefluorinated acrylic polymer additive had comparable gloss, distinctnessof image, haze and hardness and had an acceptable color.

EXAMPLE 2

A clear coating composition D was prepared by mixing together thefollowing constituents:

    ______________________________________                                                              Parts by Weight                                         ______________________________________                                        Acrylic Polymer I solution                                                                            215.4                                                 (prepared in Example 1)                                                       "Cymel" 1168 (alkylated melamine formaldehyde                                                         80.1                                                  resin)                                                                        Fluorinated acrylic polymer additive solution B                                                       10.7                                                  (prepared in Example 1)                                                       Catalyst (aromatic sulfonic acid in isopropanol)                                                      1.8                                                   Total                   308.0                                                 ______________________________________                                         Clear coating composition D was applied in the same manner as in Example      to phosphated steel panels coated with an electrocoating primer and base      coat as described in Example 1 and cured providing a clear coat that was      smooth, essentially free of craters and had an excellent appearance. The      panels were tested as in Example 1 and the test results are shown in Tabl     I.                                                                       

                                      TABLE                                       __________________________________________________________________________                                                    Soil                                     *Water                                                                            *Hexadecane                                                                         Gloss           Lab Color  Resistance                    Clear                                                                              Additive                                                                            Contact                                                                           Contact                                                                             Measured   Hardness                                                                           Angles     Test (Delta                   Coating                                                                            (Wt %)                                                                              Angle                                                                             Angle at 20°                                                                      DOI                                                                              Haze                                                                             (knoops)                                                                           L    a  b  E Units)                      __________________________________________________________________________    Control                                                                            0      75/58                                                                            0/0   86   95 11.8                                                                             9.5  87.36                                                                              -1.59                                                                            0.65                                                                             35.3                          Coating A                                                                          Additive A                                                                          107/74                                                                            64/47 81   88 3.12                                                                             12.1 87.79                                                                              -1.72                                                                            0.01                                                                             13.5                               (5.0%)                                                                   Coating B                                                                          Additive B                                                                          109/74                                                                            69/39 87   93 11.7                                                                             11.0 87.06                                                                              -1.38                                                                            -0.72                                                                            4.7                                (2.0%)                                                                   Coating C                                                                          Additive B                                                                          110/74                                                                            65/37 86   97 10.9                                                                             9.4  86.58                                                                              -1.45                                                                            -0.97                                                                            5.3                                (5.0%)                                                                   Coating D                                                                          Additive B                                                                          112/74                                                                            74/21 85   96 19.4                                                                             10.3 86.67                                                                              -1.44                                                                            -0.83                                                                            7.5                                (3.5%)                                                                   __________________________________________________________________________     *Advancing/Receding contact angle for water and hexadecane.              

We claim:
 1. A coating composition containing about 45-80% by weight of a binder and 20-55% by weight of a carrier liquid; wherein the binder comprises(A) about 30-89% by weight, based o the weight of the binder, of an acrylic polymer consisting of polymerized hydroxyl containing monomers of hydroxy alkyl (meth)acrylate having 1-4 carbon atoms in the alkyl group and polymerized monomers selected from the group consisting of alkyl (meth)acrylates having 1-18 carbon atoms in the alkyl groups, styrene or any mixtures of the above and the acrylic polymer having a weight average molecular weight of about 2,000-20,000 determined by gel permeation chromatography, (B) about 1-20% by weight, based on the weight of the binder, of an acrylic polymeric additive consisting of about 5-90% by weight, based on the weight of the additive, of polymerized monomers selected from the group consisting of alkyl (meth)acrylates having 1-18 carbon atoms in the alkyl groups, styrene or any mixtures of the above and 10-95% by weight, based on the weight of the additive, of polymerized fluoro alkyl containing monomer represented by the formula ##STR11## where R is selected from the group consisting of hydrogen or an alkyl group having 1-2 carbon atoms, X is a divalent radical and R_(f) is a fluoro alkyl containing group having 4-20 carbon atoms and the acrylic polymer having a weight average molecular weight of about 1,000-15,000 determined by gel permeation chromatography, and (C) about 10-50% by weight, based on the weight of the binder, of an organic crosslinking agent; andwhere a cured layer of the coating of the composition has a combination of advancing water contact angle of at least 100° and a hexadecane advancing contact angle of at least 40°.
 2. The coating composition of claim 1 in which the flouro alkyl containing monomer is represented by the formula ##STR12## where R is as defined in claim 1, n is an integer of 1-11 and R_(f) is a straight chain or branched chain fluoro alkyl group having 4-20 carbon atoms.
 3. The coating composition of claim 1 in which the acrylic polymeric additive consisting essentially of about 10-45% by weight, based on the weight of the additive, of polymerized acetoacetoxy alkyl (meth)acrylate having 1-4 carbon atoms in the alkyl group, 5-80% by weight, based on the weight of the additive, of polymerized monomers selected from the group consisting of alkyl (meth)acrylates having 1-18 carbon atoms in the alkyl groups, styrene or any mixtures of the above and 10-50% by weight, based on the weight of the additive, of polymerized fluoro alkyl containing monomer represented by the formula ##STR13## where R is selected from the group consisting of hydrogen or an alkyl group having 1-2 carbon atoms, n is an integer of 1-11 and R_(f) is a fluoro alkyl containing group having 4-20 carbon atoms.
 4. The coating composition of claim 3 in which the acrylic polymeric additive consists essentially of polymerized monomers of an alkyl methacrylate having 2-6 carbon atoms in the alkyl group, an alkyl acrylatc having 2-8 carbon atoms in the alkyl group, an acetoacetoxy alkyl (meth)acrylate having 1-4 carbon atoms in the alkyl group, styrene and a fluoro alkyl containing monomer wherein R is CH₃, n is 2 and R_(f) is a fluoro alkyl group having 4-20 carbon atoms and the crosslinking agent is an organic polyisocyanate crosslinking agent and the cured layer of the composition has an advancing water contact angle of 100-120° and a hexadecane advancing contact angle of 45-85° C.
 5. The coating composition of claim 4 in which the acrylic polymeric additive consists essentially of butyl methacrylate, butyl acrylate, styrene, acetoacetoxy ethyl methacrylate and the fluoro alkyl containing monomer.
 6. The coating composition of claim 1 in which the fluoro alkyl containing monomer is represented by the formula ##STR14## where R is as defined in claim 1,R¹ is a fluoro alkyl group having 4-12 carbon atoms, R² is an alkyl group having 1-4 carbon atoms and n is an integer of 1-4.
 7. The coating composition of claim 1 in which the crosslinking agent is an organic polyisocyanate selected from the group of aromatic diisocyanate, aliphatic diisocyanate, cycloaliphatic diisocyanate, aromatic triisocyanate, aliphatic triisocyanate or an oligomer of a diisocyanate.
 8. The coating composition of claim 7 in which the crosslinking agent is a fluorinated organic polyisocyanate comprising an adduct of a fluorinated monofunctional alcohol and an organic polyisocyanate where the fluorinated monofunctional alcohol is represented by the formula ##STR15## where R_(f) is a fluoroalkyl containing group having at least 4 carbon atoms, Y is a divalent radical, R³ is H or an alkyl group having 1-4 carbon atoms, n is 0-1 and m is 1-30, provided that when n is 0, then m must be equal to or greater than 1, and where about 0.1-33 mole percent of active isocyanate groups are reacted with the fluorinated monofunctional alcohol.
 9. The coating composition of claim 1 in which the crosslinking agent is an alkylated melamine formaldehyde crosslinking agent.
 10. The coating composition of claim 3 containing about 45-80% by weight of a binder and 20-55% by weight of an organic carrier liquid; wherein the binder comprises(A) about 30-89% by weight, based on the weight of the binder, of an acrylic polymer consisting essentially of about 20-50% by weight, based on the weight of the acrylic polymer, of polymerized monomers of hydroxy alkyl (meth)acrylate having 1-4 carbon atoms in the alkyl groups, and 50-80% by weight, based on the weight of the acrylic polymer, of polymerized monomers selected from the group consisting of alkyl (meth)acrylates having 1-18 carbon atoms in the alkyl group, styrene or any mixtures of the above and the acrylic polymer having a weight average molecular weight of about 2,000-20,000 determined by gel permeation chromatography, (B) about 1-20% by weight, based on the weight of the binder, of an acrylic polymeric additive consisting essentially of about 10-45% by weight, based on the weight of the additive, of polymerized monomers of acetoacetoxy alkyl (meth) acrylate having 1-4 carbon atoms in the alkyl groups, 5-80% by weight, based on the weight of the additive, of polymerized monomers selected from the group consisting of alkyl (meth)acrylates having 1-18 carbon atoms in the alkyl group, styrene or any mixtures of the above and 10-50% by weight, based on the weight of the additive, of polymerized fluoro alkyl containing monomer represented by the formula ##STR16## where R is selected from the group consisting of hydrogen or an alkyl group having 1-2 carbon atoms, n is an integer of 1-11 and R_(f) consists of a straight chain or branched chain fluoro alkyl containing group having 4-20 carbon atoms and the acrylic polymer having a weight average molecular weight of about 1,000-10,000 determined by gel permeation chromatography, and (C) about 10-50% by weight, based on the weight of the binder, of an organic polyisocyanate crosslinking agent selected from the group consisting of aromatic diisocyanate, aliphatic diisocyanate, cycloaliphatic diisocyanate, aromatic triisocyanate, aliphatic triisocyanate or an oligomer of a diisocyanate; andwhere a cured layer of the coating of the composition has a combination of advancing water contact angle of 100-120° and a hexadecane advancing contact angle of 40-85°.
 11. The coating composition of claim 10 containing about 0.1-10% by weight, based on the weight of the binder, of ultraviolet light stabilizer or an antioxidant or mixtures thereof.
 12. A substrate coated with a dried and cured layer of the composition of claim
 1. 13. A substrate coated with a pigmented base coat which is coated with a clear layer of the dried and cured composition of claim
 1. 